Lyla, Lightsworn Sorceress

During your Main Phase: You can target 1 Spell/Trap Card your opponent controls; change this card you control from face-up Attack Position to face-up Defense Position, and destroy that target, but this card's battle position cannot be changed until the end of your next turn, except with a card effect. During each of your End Phases: Send the top 3 cards of your Deck to the Graveyard. You must control this face-up card to activate and to resolve this effect.